Rare skills = yes / Supply and Demand
I believe this depends on your skill set and qualifications. For example, a SAP programmer with specific modules that are in high demand will most likely find a job lead if they post their profile online or apply. The same would hold true for a physician with rare skills; however, doctors in general use word of mouth and very rarely resort to posting their resume or searching online. In addition to the positions listed above, this also pertains to other jobs that are in high demand as well. Personally, I resort to using friends and previous co-workers when looking for a new position, but from my experience, job borads are just one of the tools we have at our disposal and should not be ignored.
Sources: I implement HRIS systems along with company job boards and my wife is a physician.
